AAD: Acute aortic dissection; CT: Computed tomography; MRI: Magnetic resonance imaging; TEE: Transesophageal echocardiography; TTE: Transthoracic ehocardiography; CTA: CT Angiography; RCC: Right coronary cusp; ED: Emergency department; OR: Operating room

Acute ascending aortic rupture is exceedingly rare and portends an extremely dismal prognosis. Stanford Type A acute aortic dissections (AAD) classically present with new onset tearing chest or back pain and may manifest as cardiogenic shock from acute aortic insufficiency or coronary malperfusion, cardiac tamponade, and/or cerebral, spinal, mesenteric, or extremity malperfusion. While immediate diagnosis is imperative, AAD often mimics more common problems such as myocardial infarction, pulmonary embolism, and other abdominal conditions which can delay prompt diagnosis and treatment. Aortic free wall rupture can occur if left untreated. In the US, the initial diagnostic study is most commonly computed tomography (CT) (used first in 69%) of cases, followed by echocardiography (25%), magnetic resonance imaging (MRI) (4%) and aortography (2-3%) [1]. Over the past few decades, use of transesophageal echocardiography (TEE) has decreased as the preferred initial diagnostic study due to the invasive procedure and need for sedation [2].

Initial hemodynamic perturbations associated with AAD have far-reaching implications with regard to prognosis. Hypotension (<90 mmHg systolic) is associated with much higher rates of in-hospital adverse events as well as an independent predictor of death [3]. Additionally, presence of hemopericardium, identified in 18.7% of patients with Type A AAD in a recent study, resulted in significantly higher mortality than patients without pericardial effusion [4].

In this case, a 68-year-old male presented to the ED with a GCS of 9 after a syncopal episode at home following a one-day history of generalized malaise and fatigue. Initial findings included severe hypotension and a moderate size pericardial effusion on CT angiography (CTA). Follow-up transthoracic echocardiogram (TTE) demonstrated moderate aortic insufficiency and concern for a possible ascending aortic flap. A follow up TEE confirmed an aortic disruption/dissection on the anterior aortic root as well as severe aortic regurgitation with perforation of the right coronary cusp (RCC). The patient underwent emergent surgery with a successful Bentall procedure and was transferred to the ICU without complications.

A 68-year-old male with a past medical history significant for hypertension, concentric left ventricular hypertrophy (~2.6 cm), and alcohol abuse presented to the emergency department (ED) after a syncopal event at home. History was obtained from the patient’s wife who reported she had found him collapsed in the bathroom after a previous twenty-four-hour history of generalized malaise and fatigue. His wife reported that patient had high blood pressures throughout the day prior to collapsing.

The patient was hypotensive (non-invasive blood pressure 69/47) and bradycardic on presentation. Resuscitation was started with three liters of crystalloid. EKG twelve-lead was performed with anterior lead ST elevations and flipped T waves with reciprocal changes in the lateral leads. An arterial line was placed, and advanced hemodynamic monitoring showed decreased cardiac output. A right internal jugular central line was placed, and norepinephrine infusion was started for ongoing hypotension. CT- with pulmonary embolism (PE) protocol study showed left lower lobe segmental PE, a pericardial effusion with concern for hemopericardium with mass effect on right ventricle, and complex fluid adjacent to the ascending aorta concerning for intramural hematoma. Follow-up CTA was obtained which reconfirmed the hemopericardium. The initial read from the CTA indicated there was no acute aortic syndrome. The patient’s blood pressure improved (110/63) while in the ED and cardiology was consulted for further evaluation. Labs at this time were significant for a troponin of 0.06 (ng/mL), lactic acidosis of 8.8 (mmol/L), and urine drug screen positive for amphetamines.

On TTE, a large pericardial effusion was noted anterior to the right ventricle in the sub-costal view. Right ventricular end diastolic collapse was noted consistent with tamponade physiology. Homogenous material was seen in the pericardial effusion, consistent with hematoma. The patient was taken emergently to the cardiac catheterization suite for pericardiocentesis where 410 ml of bloody fluid was drained.

Post-procedural TTE demonstrated trivial pericardial effusion as well as aortic root dilatation of 5.3 cm at the sinus of valsalva with effacement of the sinotubular junction, which measured 4.8 cm. A possible dissection flap was noted on the ascending aorta adjacent to the RCC. There was no dissection noted in the descending aorta. Follow-up TEE demonstrated severe aortic regurgitation now due to annular dilatation resulting in inadequate leaflet coaptation. A dissection flap was confirmed in the sinus on the aortic side of the RCC. Systolic function was preserved with an EF of 50-55%.

Cardiothoracic surgery was consulted for emergent surgical evaluation. Further history was obtained at this point with the patient reporting shortness of breath and chest pain that radiated up his neck for the past couple of weeks. Patient was consented for surgery and emergently taken to the operating room (OR). At this time the patient required infusions of nitroglycerin, esmolol and nicardipine to maintain normotension. In the OR the patient was intubated and positive pressure ventilation was initiated uneventfully. Intra-operative TEE confirmed an aortic disruption/dissection on the anterior aortic root distal to the RCC as well as severe aortic regurgitation with perforation of the RCC. No obvious false lumen was identified. Initial findings from the surgeon confirmed a tear in the aortic root above the left main coronary ostium extending to just above the right coronary ostium. There was a contained rupture about 3 cm in length with overlying hematoma which was buttressed by the main pulmonary artery. A Bentall procedure was performed with a 25mm Avalus™ (Medtronic, Minneapolis, MN) inside a 28 mm Gelweave Valsalva graft. A Cabrol-left main procedure with 10 mm Gelweave™ (Terumo Aortic, Sunrise, FL) graft was utilized and the right coronary button was directly reimplanted. The patient was transferred to the CICU intubated, sedated, and hemodynamically stable.

Post-operative course was complicated by transaminitis with possible cirrhosis due to patient’s history of alcohol abuse which led to coagulopathy and bleeding on POD #2. For this reason, anticoagulation was held. Patient was placed on the institutional alcohol withdrawal protocol. The patient required one unit of red blood cells on POD #3. The patient was extubated on POD #4 after control of his delirium tremens. The patient experienced paroxysmal atrial fibrillation throughout his hospital stay requiring cardioversion and medical management. The patient also required cardiology consultations to optimize blood pressure control and investigate potential secondary hypertension throughout his hospitalization. The patient was discharged home on POD #19.

This case demonstrated the importance of a high index of suspicion for acute aortic dissection despite an initial negative CTA. While rare that a CTA would miss an ascending AAD, this patient’s initial severe hypotension and hemopericardium should have resulted in immediate surgical intervention instead of pericardiocentesis. Although this patient’s ascending AAD and rupture were eventually identified and repaired with a positive outcome, this patient could have had a significantly different course.

When the area of interest is the aortic root, echocardiography may be preferred over non-gated CTA due to the ability to visualize aortic root. Additionally, CTA is vulnerable to significant motion artifact, which may be exacerbated by tachycardia in the setting of hypovolemia and shock [5]. Conversely, when the areas of interest are the distal ascending aorta, aortic arch, and descending thoracic aorta, CTA and MRA are both preferred over echocardiography [5]. The sensitivity of CTA for aortic dissection is 87-94%, with TEE having a sensitivity around 96% [6]. While CTA was an adequate first line imaging choice, further investigation with TEE could have expedited this patient’s time to the OR. However, this patient also presented with such hemodynamic instability that the sedation and intubation required to image in this way would not be recommended for purely diagnostic purposes.

This case also represented a challenge due to the atypical presentation of AAD and subsequent rupture. According to the 2000 International Registry of Acute Aortic Dissection (IRAD), only 12.7% of type A AADs presented with syncope and only 13% presented with a shock (SBP <80 mmHg) or tamponade physiology [7]. This minority of patients likely represents the fact that most patients experiencing syncope and shock fail to survive long enough to make it to a hospital. While diagnostic accuracy continues to improve, case reports from 1990 suggest that the diagnosis of AAD was missed initially in 38% of cases with 28% only being identified in post-mortem examination [8]. Other, more recent studies suggest that initial misdiagnosis rates could still be between 16-39% [9].

While there is extensive literature on the diagnosis and treatment of AADs, there is a paucity of literature on contained aortic rupture progressing from AAD. A case series from Yale documented only 7 patients that presented with spontaneous acute ascending aortic rupture from 2012-2017, only 2 of which had pre-operative diagnoses of dissection (diagnosed by CTA) [10]. Another unresolved part of this case is the patient’s previously unreported history of chest pain prior to presentation at the hospital. This may represent a history consistent with subacute aortic dissection and explain why this patient’s aorta ruptured at 5.3 cm although substantial risk for rupture is generally accepted at diameters greater than 5.5 cm [11]. However, recent evidence suggests that the aortic diameter increases substantially (7.65 mm in one study) due to the aortic dissection itself, meaning aortas are dissecting at significantly smaller sizes than previous studies have suggested, and the rupture in this case may not be unique in presentation [12].

The presence of the pericardial effusion raises the most interesting clinical decision point involved in this case. If the dissection had been discovered concomitantly, pericardial drainage is only indicated if the patient is hemodynamically unstable (and unlikely to survive until taken to the OR) or elderly and unlikely to survive any major operation [13]. In the former, clinicians should perform pericardiocentesis with the goal of withdrawing only as much fluid as is necessary to restore perfusion to the heart as the procedure is associated with ongoing hemorrhage and associated mortality [14].

Pericardiocentesis is avoided in proximal aortic dissections because of the increased risk of worsening tamponade after a transient relief of intracardial pressure. The initial pericardial effusion results from leakage of blood from the false lumen into the pericardial space. While exact mechanisms are unknown, this leakage is often transient and minimal due to an intimal flap or local tissues acting as a valve or a thrombus forming to prevent further flow. The initial tamponade itself may also limit additional leakage by reducing cardiac output, aortic pressure, and contractility. This initial tamponade can stabilize for a brief period whereby no additional communication is taking place and the dissection does not propagate. Pericardiocentesis raises the risk that one of these stabilizing factors is upset and instead of a leak, unrestricted blood flow takes place. Increased pressures resulting from pericardiocentesis can dislodge a protective thrombus as well as lead to retrograde propagation of a dissection into the aortic root, creating free communication with the pericardial space [15]. European Society of Cardiology guidelines (2015) have stated that in the setting of aortic dissection, controlled pericardial drainage can be attempted with a goal of removing only enough blood to stabilize the patient and achieve a systolic blood pressure of about 90 mmHg [16]. In this case, the patient’s severe hypotension was able to be corrected with the use of crystalloids and limited vasopressors so pericardiocentesis would not have been indicated.

This case is remarkable because the patient was able to tolerate complete drainage of his pericardial effusion as well as systolic pressures elevated far above 90 mmHg before the dissection was identified, and he was emergently taken to the OR. The exact reason for this patient’s avoidance of acute decompensation is unknown but is likely due to a significant thrombus of the contained aortic root rupture which failed to dislodge during the aftermath of the pericardial drainage. This thrombus prevented the open communication between dissection flap and pericardial space which often leads to rapid hemorrhage or reestablishment of cardiac tamponade, subsequent electromechanical dissociation, and death.

This case demonstrates the importance of possessing the clinical acumen to quickly identify cardiac tamponade, and in a patient presenting with suspected hemopericardium, one should have a high suspicion for an acute aortic dissection/rupture. The initial management is stabilization, controlling blood pressure, and expeditious surgical repair. The patient’s history of uncontrolled hypertension and the echocardiographic finding of an aortic root aneurysm likely set the stage for this aortic catastrophe. Despite an initial delay in diagnosis, a multidisciplinary effort led to hemodynamic stabilization and transfer to the operating room for his life-saving intervention.